Amazon's verified purchase is ridiculously easy to game - a competitor of mine has 10 - 20 accounts shilling all over that store with verified purchases... once you consider the 70% you get back you're only paying $0.30 or w/e to verify the purchase, or nothing if you just set your app free then revert it to paid which will give you a 2 - 3 hour window. If someone from Amazon is reading I'd love to ping you with names!

What I look for is a solid mix of 2/3/4 ratings, it's difficult to fake that, on the Play store you can balance the # of downloads against the # of reviews too and avoid stuff where 30 - 100 percent of 'downloaders' leave 5 star reviews.

Amazon's "Verified Purchase" system is easily gamed by setting up a highly-discounted short-run coupon code which is then distributed to professional reviewers. These reviewers receive their item with the implication that they'll wink wink nudge nudge review the product accordingly. It's pretty easy to identify these garbage 5-star reviews once you learn to spot them though. They're everywhere and frequently used for product launches to help snowball sales.

No I mean in the sense that I don't "trust high star rating but I'm inclined to trust lower star ratings." I find myself unconsciously weighting individual really poor review much higher than general good reviews.